Mortgage Servicing Rights and Related Liabilities - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Forward MSRs Sold
Servicing Assets at Fair Value [Line Items]
Unpaid principal balance sold	$ 5,163	$ 1,070
Forward MSRs Sold, Subservicing Retained
Servicing Assets at Fair Value [Line Items]
Principal amount outstanding on mortgage servicing rights	$ 3,937	$ 960

This is the sum of principal amount outstanding for both securitized and unsecuritized loans of all types.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719

Name:	us-gaap_PrincipalAmountOutstandingOnLoansManagedAndSecuritized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant